ABSTRACT: Current state of the art in diabetes indicates the possibility that glucose intolerance is a continuum starting from the lower limits of impaired G.T.T. up to severe hyperglycemia. Environmental factors seem to play a crucial role in the process of conversion of a glucose tolerant into a glucose intolerant person in the decompensation of chemical into overt diabetes, and in the development of the macro and microvascular complications associated with chemical and overt diabetes. Obesity and hypertension are associated with increased risk. Dietary factors are involved. It is proposed to study a random sample of 5,600 first and second generation Israeli residents of four ethnic groups born between 1912-1941, stratified by ethnic groups, age sex and length of residence in the country. The following variables will be studied for the purpose of identification of risk factors: 1. Relative weight - current and at previous measurement 5-8 years ago. 2. Blood pressure level-current and previous measurement 5-8 years ago. 3. Glucose tolerance test. 4. Insulin response curve. 5. Hemoglobin A1c. 6. High density lipoprotein cholesterol 7. Low density lipoprotein cholesterol. 8. Total Lipids. 9. Blood Urea. 10. Urinary high molecular weight proteinuria. 11. E.C.G. 12. Physical Examination. 13. Morbidity at previous examination 5-8 years ago and morbidity and morality during the follow-up period. 14. Drug profile as reported in current and previous examination 5-8 years ago. 15. Dietary profile obtained by interview. The study group will be available for future follow-up to determine the natural history of glucose intolerance. It is hoped that preventable environmental risk factors will be identified.